Unable to read memory in web method

Question

I'm getting this error in my application. I have a web method that I am calling from javascript.

The error I'm getting in the visual studio inspector:

The method signature:

The JSON I'm posting to the method:

It's a very obscure message to me. What do I do next?

Answer 1

The answer is simple. I accidentally set the build configuration to release instead of debug which caused this behavior.

What is the difference between Debug and Release in Visual Studio?